/* getline.c -- Replacement for GNU C library function getline

Copyright (C) 1993 Free Software Foundation, Inc.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.  */

/* Written by Jan Brittenson, bson@gnu.ai.mit.edu.  */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <sys/types.h>
#include <stdio.h>
#include <assert.h>
#include <errno.h>

#if STDC_HEADERS
#include <stdlib.h>
#else
char *malloc(), *realloc();
#endif

/* Always add at least this many bytes when extending the buffer.  */
#define MIN_CHUNK 64

/* Read up to (and including) a TERMINATOR from STREAM into *LINEPTR
+ OFFSET (and null-terminate it). *LINEPTR is a pointer returned from
malloc (or NULL), pointing to *N characters of space.  It is realloc'd
as necessary.  Return the number of characters read (not including the
null terminator), or -1 on error or EOF.  On a -1 return, the caller
should check feof(), if not then errno has been set to indicate
the error.  */

int
getstr(lineptr, n, stream, terminator, offset)
char **lineptr;
size_t *n;
FILE *stream;
char terminator;
int offset;
{
    int nchars_avail;		/* Allocated but unused chars in *LINEPTR.  */
    char *read_pos;		/* Where we're reading into *LINEPTR. */
    int ret;

    if (!lineptr || !n || !stream)
    {
        errno = EINVAL;
        return -1;
    }

    if (!*lineptr)
    {
        *n = MIN_CHUNK;
        *lineptr = malloc(*n);
        if (!*lineptr)
        {
            errno = ENOMEM;
            return -1;
        }
    }

    nchars_avail = (int)(*n - offset);
    read_pos = *lineptr + offset;

    for (;;)
    {
        int save_errno;
        register int c = getc(stream);

        save_errno = errno;

        /* We always want at least one char left in the buffer, since we
        always (unless we get an error while reading the first char)
        NUL-terminate the line buffer.  */

        assert((*lineptr + *n) == (read_pos + nchars_avail));
        if (nchars_avail < 2)
        {
            if (*n > MIN_CHUNK)
                *n *= 2;
            else
                *n += MIN_CHUNK;

            nchars_avail = (int)(*n + *lineptr - read_pos);
            *lineptr = realloc(*lineptr, *n);
            if (!*lineptr)
            {
                errno = ENOMEM;
                return -1;
            }
            read_pos = *n - nchars_avail + *lineptr;
            assert((*lineptr + *n) == (read_pos + nchars_avail));
        }

        if (ferror(stream))
        {
            /* Might like to return partial line, but there is no
            place for us to store errno.  And we don't want to just
            lose errno.  */
            errno = save_errno;
            return -1;
        }

        if (c == EOF)
        {
            /* Return partial line, if any.  */
            if (read_pos == *lineptr)
                return -1;
            else
                break;
        }

        *read_pos++ = c;
        nchars_avail--;

        if (c == terminator)
            /* Return the line.  */
            break;
    }

    /* Done - NUL terminate and return the number of chars read.  */
    *read_pos = '\0';

    ret = (int)(read_pos - (*lineptr + offset));
    return ret;
}

int
getline(lineptr, n, stream)
char **lineptr;
size_t *n;
FILE *stream;
{
    return getstr(lineptr, n, stream, '\n', 0);
}